It is known to provide a loom with two separate weftfilament feeds so that, if one of the feeds jams or runs out, the other can take over. Thus the loom can keep running while the problem with the nonoperational feed is cured.
In European patent 195,469 issued 29 March 1989 (based on Belgian patent application 60,647 filed 19 March 1985 by J. Waelhens and assigned to Weefautomaten Picanol) such a loom is described where a plurality of sensors are provided along the path of the weft filament in each of the two separate weft feed units. These sensors monitor the conditions of the weft filaments and, on detection of a defect in the currently operating unit, switch the system over to the other feed unit.
Such a system thus requires two fairly elaborate sets of sensors in addition to the normally provided sensors. This is in addition to the normally provided system that detects if the weft filament has been properly inserted in the warp. Furthermore this arrangement cannot be adapted to a shuttleless loom in which the weft filament is shot by compressed gas across the warp because it is much more difficult to provide an air-insertion machine with a plurality of inserters than it is to provide multiple inserters on a standard mechanical system.